In a cable television system, a set-top box is customarily used at the consumer's television to receive incoming television signals from the distribution point, such as the cable head end. The incoming stream of data content is managed typically through the use of cryptographic protocols that utilize key data stored at the distribution point and at the set top box. The use of these cryptographic protocols helps to ensure that unauthorized individuals will not access the program content. However, such unauthorized individuals will often attempt to defeat these security measures. One such attempt is to try and obtain a set top box that has already been loaded with the cryptographic key data and clone that device. A cloned set top box could be very damaging to a cable operator in that it could potentially be duplicated many times over and thus allow pirating of the cable operator's programming.
Thus, cable operators are very careful about loading set top boxes with security data. The initial data that is loaded into a unit is very important to keep secure, as it lays the foundation for all future security measures implemented by the set top box.
One of the steps implemented as part of the initialization process for a set top box is to load a unit address. This unit address allows the cable operator to identify any particular device in its system. The unit address is normally assigned via the use of a certificate downloaded to a set top box.
The use of application specific integrated circuits (ASIC's) are useful in providing security measures for devices involved in secure operations. Such devices can be configured with initial security parameters that are not detectable by reverse engineering. As a result, they can be programmed at the factory with initial security settings and then loaded with additional security data. After being loaded with the additional security data, they can be physically altered to prevent unauthorized access to their data.
Such ASIC's sometimes must work with other parts of a device, such as firmware in a set top box, in order to implement secure operations. However, since such firmware does not have built in security protections, as is the case with the ASIC itself, it is difficult to initiate the firmware with initial security data.